1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_CONTEXT_TRACKING_H
3 #define _LINUX_CONTEXT_TRACKING_H
4 
5 #include <linux/sched.h>
6 #include <linux/vtime.h>
7 #include <linux/context_tracking_state.h>
8 #include <linux/instrumentation.h>
9 
10 #include <asm/ptrace.h>
11 
12 
13 #ifdef CONFIG_CONTEXT_TRACKING
14 extern void context_tracking_cpu_set(int cpu);
15 
16 /* Called with interrupts disabled.  */
17 extern void __context_tracking_enter(enum ctx_state state);
18 extern void __context_tracking_exit(enum ctx_state state);
19 
20 extern void context_tracking_enter(enum ctx_state state);
21 extern void context_tracking_exit(enum ctx_state state);
22 extern void context_tracking_user_enter(void);
23 extern void context_tracking_user_exit(void);
24 
25 static inline void user_enter(void)
26 {
27 	if (context_tracking_enabled())
28 		context_tracking_enter(CONTEXT_USER);
29 
30 }
31 static inline void user_exit(void)
32 {
33 	if (context_tracking_enabled())
34 		context_tracking_exit(CONTEXT_USER);
35 }
36 
37 /* Called with interrupts disabled.  */
38 static __always_inline void user_enter_irqoff(void)
39 {
40 	if (context_tracking_enabled())
41 		__context_tracking_enter(CONTEXT_USER);
42 
43 }
44 static __always_inline void user_exit_irqoff(void)
45 {
46 	if (context_tracking_enabled())
47 		__context_tracking_exit(CONTEXT_USER);
48 }
49 
50 static inline enum ctx_state exception_enter(void)
51 {
52 	enum ctx_state prev_ctx;
53 
54 	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) ||
55 	    !context_tracking_enabled())
56 		return 0;
57 
58 	prev_ctx = this_cpu_read(context_tracking.state);
59 	if (prev_ctx != CONTEXT_KERNEL)
60 		context_tracking_exit(prev_ctx);
61 
62 	return prev_ctx;
63 }
64 
65 static inline void exception_exit(enum ctx_state prev_ctx)
66 {
67 	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) &&
68 	    context_tracking_enabled()) {
69 		if (prev_ctx != CONTEXT_KERNEL)
70 			context_tracking_enter(prev_ctx);
71 	}
72 }
73 
74 static __always_inline bool context_tracking_guest_enter(void)
75 {
76 	if (context_tracking_enabled())
77 		__context_tracking_enter(CONTEXT_GUEST);
78 
79 	return context_tracking_enabled_this_cpu();
80 }
81 
82 static __always_inline void context_tracking_guest_exit(void)
83 {
84 	if (context_tracking_enabled())
85 		__context_tracking_exit(CONTEXT_GUEST);
86 }
87 
88 /**
89  * ct_state() - return the current context tracking state if known
90  *
91  * Returns the current cpu's context tracking state if context tracking
92  * is enabled.  If context tracking is disabled, returns
93  * CONTEXT_DISABLED.  This should be used primarily for debugging.
94  */
95 static __always_inline enum ctx_state ct_state(void)
96 {
97 	return context_tracking_enabled() ?
98 		this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
99 }
100 #else
101 static inline void user_enter(void) { }
102 static inline void user_exit(void) { }
103 static inline void user_enter_irqoff(void) { }
104 static inline void user_exit_irqoff(void) { }
105 static inline enum ctx_state exception_enter(void) { return 0; }
106 static inline void exception_exit(enum ctx_state prev_ctx) { }
107 static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
108 static inline bool context_tracking_guest_enter(void) { return false; }
109 static inline void context_tracking_guest_exit(void) { }
110 
111 #endif /* !CONFIG_CONTEXT_TRACKING */
112 
113 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
114 
115 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
116 extern void context_tracking_init(void);
117 #else
118 static inline void context_tracking_init(void) { }
119 #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
120 
121 /* must be called with irqs disabled */
122 static __always_inline void guest_enter_irqoff(void)
123 {
124 	/*
125 	 * This is running in ioctl context so its safe to assume that it's the
126 	 * stime pending cputime to flush.
127 	 */
128 	instrumentation_begin();
129 	vtime_account_guest_enter();
130 	instrumentation_end();
131 
132 	/*
133 	 * KVM does not hold any references to rcu protected data when it
134 	 * switches CPU into a guest mode. In fact switching to a guest mode
135 	 * is very similar to exiting to userspace from rcu point of view. In
136 	 * addition CPU may stay in a guest mode for quite a long time (up to
137 	 * one time slice). Lets treat guest mode as quiescent state, just like
138 	 * we do with user-mode execution.
139 	 */
140 	if (!context_tracking_guest_enter()) {
141 		instrumentation_begin();
142 		rcu_virt_note_context_switch(smp_processor_id());
143 		instrumentation_end();
144 	}
145 }
146 
147 static __always_inline void guest_exit_irqoff(void)
148 {
149 	context_tracking_guest_exit();
150 
151 	instrumentation_begin();
152 	/* Flush the guest cputime we spent on the guest */
153 	vtime_account_guest_exit();
154 	instrumentation_end();
155 }
156 
157 static inline void guest_exit(void)
158 {
159 	unsigned long flags;
160 
161 	local_irq_save(flags);
162 	guest_exit_irqoff();
163 	local_irq_restore(flags);
164 }
165 
166 #endif
167